If you stay on paved roads, then from Las Vegas north, there just won't be that many roads, except for places where you are entering/leaving a larger metro area. There will likely be days when you spend the entire day riding one highway. So the issue becomes less about "where do I turn" and more about, "what is next town or point of services".

With that in mind, I tend to split my "navigating" into three overall time periods:

1. In advance of the trip:
* I make sure I have the rough "time budget" of how long it might take.
* I check some of the big parameters like climate. For example, Las Vegas itself can get fairly warm even in early May, whereas some of the highest seasonal passes are only getting open then. So check rough seasons, climate, precipitation, etc so I bring the right clothing and prepare.
* I read others journals of similar trips, mostly to get insights of what others have learned and whether there is information I might borrow e.g. services, water stops, camping opportunities, etc.

2. On the trip, but night before riding (or sometimes more than one night):
* I look up the rough choices for the day. For example, "US 95N to OR 31 @ 26 miles", "small towns @ 26 and 80 miles, camping @ 64 miles".
* Often I'll write this info down on a 3x5 card and that is all I need to navigate the next day.
* Often, I'll do a quick online search to find potential services.

3. Navigating during the day
* Follow my previous night's navigating cards. Make local choices along the way. For example, if turns out windier than expected, I might stop short. If having good day and making additional distance, might go a bit further. I might also talk with locals I meet.

As far as paper maps, books and GPS go, I end up with a mixture:
-- In time frame #1, I mostly use my computer at home.
-- In time frame #2, I'll have paper maps, but also look up some details on cell phone or laptop if I have it with me. Dependent on finding working wifi, which is always fun
-- In time frame #3, mostly following local signs and using cue cards. Occasionally might consult GPS/phone but on a trip like one through American or Canadian west, that is more exception than rule.

More detailed navigation becomes a bit different in a denser populated area like US East Coast or parts of Europe.